Plants use scent, warmth to lure insects

Washington  Think about strong perfume and a threesome, and what do you get?

No, try again.

The correct answer is - reproduction by an ancient type of plants called cycads.

Cycads have put their own special spin on the process, scientists report in today's issue of the journal Science.

Male cycads produce cones that open and emit a fragrance that attracts insects called thrips, which enter the cones and become covered with pollen, according to the research team led by Irene Terry of the University of Utah.

Then the male cycads heat up - raising the temperature as much as 25 degrees Fahrenheit - and produce a much stronger odor, driving the thrips out.

The thrips, looking for more cycads, notice the attractive scent of female cycads and enter their cones, bringing the male pollen to the female plants.

The scientists call this "push-pull pollination."

"People think of plants as just sitting there and looking pretty and sending out some odors to attract pollinators, but these cycads have a specific sexual behavior tuned to repel, attract and deceive the thrips that pollinate them," Terry said.